TOOL PERFORMANCE WHEN DRILLING SINTERED NICKEL-BASE ALLOY WITH UNCOATED CARBIDE TOOL

摘要

Drilling of Sintered nickel alloy under flood cooling with uncoated carbide drills at various cutting speeds and feed rates was carried out in order to evaluate the effect of cutting conditions on drill life, and chip forms. Chipping of the cutting edge was the dominant failure mode. The chipping action was initiated at the periphery of the drill due to increasing stress in the tool which tends to accelerate fatigue cracks along the cutting edges as drilling progressed. The finish drill employed at a lower feed of 0.053 mm/rev experienced chipping during the early stage of the drilling process relative to those employed for drilling at a higher feed of 0.067mm/rev due to stress (cutting load) on smaller area of the drill cutting edge. Chips generated changed from discontinuous to serrated continuous as wear on the drill increased during rough drilling operation.